Minimal access lumbar diskectomy instrumentation and method

ABSTRACT

A minimal incision maximal access system allows for maximum desirable exposure along with maximum access to the operative field utilizing a minimum incision as small as the METRx and Endius systems. Instead of multiple insertions of dilating tubes the design is a streamlined single entry device to avoid repetitive skin surface entry. The system offers the capability to expand to optimum exposure size for the surgery utilizing hinged bi-hemispherical or oval working tubes applied over an introducer obturator which is controllably dilated to slowly separate muscle tissue. Deeper end working and visualization areas with maximum proximal access and work dimensions are provided to makes the operative procedure safer in application and shorten the surgeons&#39;s learning curve because it most closely approximates the ability to use open microdiskectomy techniques.

FIELD OF THE INVENTION

The present invention relates to improvements in the field of minimalaccess lumbar posterior surgery and more particularly to instrumentationwhich allows for maximal access to the surgical field through thesmallest possible incision. Greater access is allowed into the workingfield while enjoying the reduction of trauma and disturbance tosurrounding tissues, which results in a reduced the time necessary tocomplete the operative procedure, increased safety of the procedure, andincreased accuracy by providing an expanded working field.

BACKGROUND OF THE INVENTION

Microscopic Lumbar Diskectomy techniques were developed and championedby Dr. Robert Williams in the late 1970's and by Dr. John McCullough inthe late 1980's and 1990's. For the first time since the advent ofLumbar Disc Surgery by Mixter and Barr in 1934 a method was introducedallowing Lumbar Disc Surgery to be performed through a small incisionsafely resulting in faster patient recovery and converting a two to fivehospital stay procedure virtually to an outpatient procedure.

The special retractors developed by Drs. Williams and McCullough howeverwere often difficult to maintain in optimum position and relied on theinterspinous and supraspinatus ligaments for a counter fixation pointseverely stretching the structures. This stretching along with theeffects of partial facectomy, diskectomy, removal of the ligamentumflavum and posterior longitudinal ligament contributed to thedevelopment of Post Diskectomy Instability. Taylor retractors were alsoused but were cumbersome, required larger incisions and often injuredthe facet joints.

Dr. William Foley in 1997 introduced a tubular system mated to anendoscope which he labeled a Minimal Endoscopic Diskectomy (MED) system.It featured sequentially dilating the Lumbar Paraspinous Musclesallowing a working channel to be advanced down to the level of operationthrough which nerve root decompression and Diskectomy Surgery could beperformed with a small incision and less muscle trauma. Improvementswere made by Dr. Foley in his second generation METRx system. However,there were several disadvantages to the MED and METRX systems.

In the MED and METRX systems, the cylindrical working channelconsiderably restricted visualization and passage of instruments. Italso compromised the “angle of approach” necessary for safe usage of theoperating instruments. This problem was proportionately aggravated withthe long length of the tube. This compromised visualization contributedto the following problems, including nerve injury, dural tear, misseddisc fragments, inadequate decompression of the lateral recess,increased epidural bleeding, difficulty controlling epidural bleeding,inadequate visualization of the neuroforamen, and inadequatedecompression of neuroforamen.

The repetitive introduction of successively larger dilators caused skinabrasion with the potential for carrying superficial skin organisms downto the deeper tissue layers hypothetically increasing the risk ofinfection. The learning curve for operating in a two dimensionendoscopic field proved to be arduous and contributed to the abovecomplications.

The attempted use of the METRx system for more complex procedures suchas fusion was further hazardous by inherent limitations.

Endius in September of 2000 then introduced a similar device whichdiffered by having an expandable foot piece to allow greater coverage ofthe operative field. However, the enlarged foot piece was unwieldy anddifficult to seat properly. Exposure of the angle of approach was alsolimited by having to operate through a proximal cylindrical tube withits limitations as described before. In comparison to the METRX systemthe working area was improved but access was again restricted by thesmaller proximal cylinder.

Both systems offered endoscopic capability but many spine surgeons choseto use an operating microscope or loupes to maintain 3-Dimensionalvisualization rather than the depth impaired 2-Dimensional endoscopicpresentation. Keeping debris off of the endoscopic lens has also provedto be a troubling challenge.

SUMMARY OF THE INVENTION

The system and method of the invention, hereinafter minimal incisionmaximal access system, includes a surgical operating system that allowsfor maximum desirable exposure along with maximum access to theoperative field utilizing a minimum incision as small as the METRx andEndius systems. The minimal incision maximal access system disclosedoffers advantages over the METRx and Endius systems in several respects.First, instead of multiple insertions of Dilating Tubes the Invention isa streamlined single entry device. This avoids repetitive skin surfaceentry. Second, the minimal incision maximal access system offers thecapability to expand to optimum exposure size for the surgery utilizinghinged bi-hemispherical or oval Working Tubes applied over an introducerObturator which is controllably dilated to slowly separate muscletissue.

Third, the minimal incision maximal access system maximizes deeper endworking and visualization area with maximum proximal access and workdimensions significantly greater than either the METRx or Endius devicesand methods. Fourth, the minimal incision maximal access system providesexpanded visual and working field to makes the operative procedure saferin application and shorten the surgeons's learning curve because it mostclosely approximates the open microdiskectomy techniques. Fifthly, theminimal incision maximal access system has a tapered ended Obturatorwhich allows for tissue spread rather than muscle tissue tear andsubsequent necrosis.

Sixth, the minimal incision maximal access system controls muscle oozinginto the operative field which is controlled by simply opening the tubesfurther. This also thereby controls the bleeding by pressure to thesurrounding tissues. Seventh, in contrast to the cylindrical tube basedsystems such as the METRx and Endius the minimal incision maximal accesssystem offers a larger working area in proportion to the working depth.For the first time this allows for a minimal access technique to beapplied to the large or obese patients. The enlarged footprint of thelonger tubes in the minimal incision maximal access system is a majordifference from any other minimal access system.

An eighth advantage of the minimal incision maximal access system isthat ist expandable design allows for excellent exposure for morecomplex procedures such as fusion and instrumentation including TLIF,PLIF, and TFIF (Transfacet Interbody Fusion), as well as allowingapplication for anterolateral lumbar disc surgery. The minimal incisionmaximal access system can also be used for cervical surgery posteriorly(foraminotomy, lateral mass instrumented fusion) as well as anteriorcervical diskectomy and fusion. The minimal incision maximal accesssystem can also be used for anterior lumbar interbody fusion be itretroperitoneal, transperitoneal or laparoscopic.

A ninth advantage of the minimal incision maximal access system is thatthe medial oval cutout of the retractors, or sleeve forming the workingtube, allows more central docking on the spine which is problematic forother devices. A medialized docking provides access for easier andbetter and safer dural retraction to address midline pathology. A tenthadvantage is had by including an anti-reflective inner surface of theretractor sleeves which eliminates unwanted glare.

An eleventh advantage of the minimal incision maximal access systemincludes the slanted and contoured distal end of the retractor sleevewhich allows minimal resistance for entry and advancement to the dockingsite. A twelfth advantage minimal incision maximal access system is theprovision of a variety of retractor tips specific for different surgicalprocedures.

A thirteenth advantage of the minimal incision maximal access system isthe provision of oval retractor sleeves for larger access requirementssuch as pedicle to pedicle exposure and especially in the case wherepedicle screw instrumentation is to be applied. This minimizesunnecessary muscle spread by providing a smaller waist profile than acircular system. A fourteenth advantage of the minimal incision maximalaccess system is that the larger retractor sleeve also features one ortwo “skirts” to cover the lateral aperture created by the spread of thetwo retractor sleeves when opened. This prevents soft tissue and muscleingress into the working cone. The skirts are attached to the workingtube either at the hinge or on one of the two halves of the sleeve.

A fifteenth advantage of the minimal incision maximal access system isthe provision of a modular design in which the retractor sleeves can bequickly removed, changed and reapplied. In this version the proximalport can also be modular and changeable to fit the needs of a specificsurgical procedure. A sixteenth advantage of the minimal incisionmaximal access system is that the retractor sleeves can be made out ofmetal, ceramic or plastic, can be opaque or translucent, and can havetips of different shapes for different applications. A seventeenthadvantage is the provision of snap lock connections of the major partsof the Invention provides for easy assembly and disengagement forcleaning and sterilization purposes.

Further, the Obturator is cannulated for carrying a central Guide PinPassage. It has a Handle component which remains superficial to theskin. The obturator houses an internal hinge device which allows forspread of the two obturator tips.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, its configuration, construction, and operation will bebest further described in the following detailed description, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a working tube with an angled uppersection and shown in position with respect to an obturator insertableinto and workable within the working tube;

FIG. 2 is a perspective assembled view illustrating the relativepositions of the obturator and working tube;

FIG. 3 is a perspective assembled view illustrates the position of theobturator after it has been inserted into the working tube;

FIG. 4 is a view taken along line 4-4 of FIG. 2 and looking into theworking tube of FIG. 1;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2 and lookinginto the hinge of working tube of FIG. 1, illustrating its hingeconnections;

FIG. 6 is an side end view of the working tube of FIGS. 1-5 andillustrating predominantly one of the rigidly connected halves of theinvention;

FIG. 7 is a side sectional view taken along line 7-7 of FIG. 6 andshowing the internal bearing pivot;

FIG. 8 is a side sectional view taken along line 8-8 of FIG. 5 andillustrating a option for external bevel for the working tube;

FIG. 9 is a side view of the working tube of FIGS. 1-8 shown with thelower portions in parallel alignment and the upper portions angled withrespect to each other;

FIG. 10 is a side view of the working tube as seem in FIG. 9 and shownwith the lower portions in an angled relationship and the upper portionsin a closer angled relationship with respect to each other;

FIG. 11 is a side view of the working tube as seen in FIGS. 9 and 10 andshown with the lower portions in a maximally angled relationship and theupper portions in parallel alignment signaling maximal spread of thelower portions in bringing the upper portions into parallel alignment;

FIG. 12 is a side view of the obturator of FIG. 1 and seen in anassembled view and emphasizing a through bore seen in dashed lineformat;

FIG. 13 is a side view of the obturator of FIG. 11 as seen in anassembled view but turned ninety degrees about its axis and emphasizingthe through bore;

FIG. 14 shows a side view of the obturator 33 of FIG. 13 with thespreading legs in an angled apart relationship;

FIG. 15 is a sectional view taken along line 14-14 of FIG. 12 and givesa sectional view from the same perspective seen in FIG. 14;

FIG. 16 is a view of the obturator similar to that seen in FIG. 15, butturned ninety degrees along its axis and illustrates the wedge as havinga narrower dimension to lend internal stability;

FIG. 17 is a closeup view of the external hinge assembly seen in FIG. 1and illustrates the optional use of a plug to cover the exposed side ofa circular protrusion;

FIG. 18 is a view taken along line 18-18 of FIG. 11 and illustrates theuse of an optional skirt having flexible members which spread from aninitial curled position to a straightened position to better isolate thesurgical field;

FIG. 19 is a view of the lower tube hemicylindrical portions 65 and 69in a close relationship illustrating the manner in which the skirtssections within their accommodation slots areas;

FIG. 20 is a cross sectional view of the a patient and spine andfacilitates illustration of the general sequence of steps taken for manyprocedures utilizing the minimal incision maximal access systemdisclosed;

FIG. 21 illustrates a fascial incisor overfitting a guide pin andfurther inserted to cut through external and internal tissue;

FIG. 22 illustrates the assembled Working Tube—Obturator being insertedinto the area previously occupied by the fascial incisor and advanced tothe operative level lamina;

FIG. 23 illustrates the obturator 33 being actuated to a spreadorientation to which automatically actuates the working tube to a spreadorientation;

FIG. 24 is a view of the working tube 35 is in place and supported, heldor stabilized in the field of view by a telescopy support arm andengagement, the opposite end of the stabilizing structure attached tothe operating table;

FIG. 25 illustrates further details of the support arm seen in FIG. 24,especially the use of a ball joint;

FIG. 26 illustrates a side view of the assembly seen in FIG. 25 is seenwith an adjustable clamp operable to hold the working tube open at anyposition;

FIG. 27 is a top view looking down upon the adjustable clamp seen inFIGS. 25-26 and shows the orientation of the working tube and adjustableclamp in fully closed position;

FIG. 28 shows a variation on the obturator seen previously in FIG. 1 andillustrates the use of handles which are brought together;

FIG. 29 illustrates a further variation on the obturator seen previouslyin FIG. 1 and illustrates the use of a central ball nut;

FIG. 30 is a sectional view taken along line 30-30 of FIG. 29 andillustrates the use of a central support block to support the centralthreaded surface;

FIG. 31 is a top view of a thin, inset hinge utilizable with any of theobturators herein, but particularly obturators of FIGS. 1 and 29;

FIG. 32 is a sectional view of the obturator of FIG. 1 within theworking tube of FIG. 1 with the wedge 51 seen at the bottom of aninternal wedge conforming space;

FIG. 33 illustrates the obturator seen in FIG. 32 as returned to itscollapsed state.

FIG. 34 illustrates a top and schematic view of the use of a remotepower control to provide instant control of the working tube using anadjustable restriction on the upper angled hemicylindrical portions ofthe working tube;

FIG. 35 is a view taken along line 35-35 of FIG. 34 and illustrating themethod of attachment of the cable or band constriction; and

FIG. 36 is a mechanically operated version of the nut and boltconstriction band seen in FIG. 25.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The description and operation of the minimal incision maximal accesssystem will be best described with reference to FIG. 1 and identifying ageneral system 31. System 31 includes an obturator 33 and a working tube35. The orientation of the obturator 33 is in a slightly displaced froma position of alignment with the working tube 35 for entry into workingtube 35 and to provide the initial carefully controlled force forspreading the working tube 35, as will be shown.

Obturator includes an upper control housing 37 and a pair of spreadinglegs 39 and 41. The spreading legs 39 and 41 are seen as coming togetherto form a conical tip and thus have hemi conical end portions. Thespreading legs 39 and 41 overfit attachment leg portions 43 and 45,respectively. At the top of the upper control housing 37 a boss 47surrounds and supports the extension of a control shaft 49. A knurledthumb knob 50 sits atop the control shaft 49 to facilitate controlledturning of the control shaft 49 to control the degree of spreading ofthe spreading legs 39 and 41. Thus spreading can be controlledindependently of pressure applied along the length of the obturator 33.

Below the upper control housing 37 is the bottom of the control shaft 49which operates against a wedge 51. The wedge 51 operates within a pairof opposing slots 52 in an upper portion 53 of the overfit attachmentleg portions 43 and 45. The lower ends of the overfit attachment legportions 43 and 45 include insertion tangs 55 which fit within insertionslots 57 of the spreading legs 39 and 41. The overfit attachment legportions 43 and 45 are pivotally attached to the upper control housing37 internally by pivot blocks 59 which fit within access apertures 60.

The working tube 35 has a first lower extending connection tang 61 and asecond lower extending connection tang 63. First lower extendingconnection tang 61 connects into a slot 64 of a lower tubehemicylindrical portion 65. The first lower extending connection tang 61is fixed to an upper angled hemicylindrical portion 67. The second lowerextending connection tang 63 connects into a slot 68 of a lower tubehemicylindrical portion 69. Second lower extending connection tang 61 isfixed to and an upper angled hemicylindrical portion 71. The upperangled hemicylindrical portion 67 has a reinforced wear plate 73 forapplying upper pressure and force on the upper angled hemicylindricalportions 67 and 71 toward each other to cause the first and second lowerextending connection tangs 61 & 63 and their connected lower tubehemicylindrical portions 65 and 69 to be urged away from each other.

At the side of the working tube 35 at the transition between the upperangled hemicylindrical portions 67 and 71 and a point just above thefirst and second lower extending connection tangs 61 & 63 is an externalhinge assembly 77. Hinge assembly 77 may include an optional first guideplate 79 and first circular protrusion 81 attached to upper angledhemicylindrical portions 67, and a first slotted plate 83 positionedadjacent to first guide plate 79 and having a slot partially surroundingthe circular protrusion 81.

Upper angled hemicylindrical portion 71 has a pair of spaced apartfacing surfaces facing a matching pair of facing surfaces of the upperangled hemicylindrical portion 67, of which a dividing line 85 is seen.Upper angled hemicylindrical portions 67 and 71 are be brought togetherto cause the first and second lower extending connection tangs 61 & 63and their connected lower tube hemicylindrical portions 65 and 69 tospread apart.

In the View of FIG. 1, the first and second lower extending connectiontangs 61 & 63 are shown in a spread apart relationship. A locking pin 87is seen which can be used to engage angularly spaced apart apertures inthe circular protrusion 81 to provide a detent action to hold theworking tube 35 in various degrees of spread. Also seen is a slightexterior bevel 89 on the lower tube hemicylindrical portions 65 and 69.

Note the angled separation of the upper angled hemicylindrical portions67 and 71 and exposing opposing surfaces 91. The angle of the opposingsurfaces 91 equals the angle of spread of the first and second lowerextending connection tangs 61 & 63.

Referring to FIG. 2, a perspective assembled view illustrates therelative positions of the obturator 33 and working tube 35 in a positionfor the obturator 33 to be inserted into the working tube 35 and beforeany spreading takes place.

Referring to FIG. 3, a perspective assembled view illustrates theposition of the obturator 33 after it has been inserted into the workingtube 35 and again before any spreading takes place. Note that the pivotaxes of the first and second lower extending connection tangs 61 & 63are on par with the pivot axes of the insertion tangs 55. The tip of theobturator 33 extends slightly beyond the bottom most part of the workingtube 35 so that the completed assembly can be smoothly urged past muscleand other tissue.

Referring to FIG. 4, a view taken along line 4-4 of FIG. 1 is a viewlooking down into the working tube 35. Other features seen include awear plate 93 located on the upper angled hemicylindrical portion 71. Inboth of the wear plates 73 and 93 a universal port 94 is provided as abore for insertion of a tool or lever to assist in bringing the upperangled hemicylindrical portions 67 and 71 into a tubular relationship.Further, an identical hinge assembly 77 on the side opposite that seenin FIG. 1 is shown with the same numbering as the components which wereseen in FIG. 1.

Also seen are a pair of opposing surfaces 95 on upper angledhemicylindrical portion 71 and a pair of opposing surfaces 97 on upperangled hemicylindrical portion 67. Also seen is a central workingaperture 99.

Referring to FIG. 5, a view taken along line 5-5 of FIG. 1 is asectional view looking down into the working tube 35. The connectivityof the structures seen in FIG. 4 are emphasized including the connectionof circular protrusion 81 to the upper angled hemicylindrical portion71, and the connection of first slotted plate 83 to upper angledhemicylindrical portion 67, and which is indicated by the matchingsection lines Further, an identical hinge assembly 77 on the sideopposite that seen in FIG. 1 is shown with the same numbering as thecomponents which were seen in FIG. 1.

Referring to FIG. 6, a view of one end of the working tube 35illustrates predominantly the second angled half portion 63. Elementsseen in FIGS. 1 and 2 are made more clear in FIG. 3.

Referring to FIG. 7, a side sectional view taken along line 7-7 of FIG.6 and shows the internal bearing pivot consisting of a slightly greaterthan hemispherical side bump projection 101 located on upper angledhemicylindrical portion 71, and a slightly less than hemispherical sidecircular groove 103 located on upper angled hemicylindrical portion 67.Also seen is the interconnect slots 64 and 68 as well as the first andsecond lower extending connection tangs 61 and 63. In the showing ofFIG. 7 an external bevel 105 is utilized

Referring to FIG. 8, a side semi-sectional view taken along line 8-8 ofFIG. 5 illustrates the integral connectivity of circular protrusion 81with the upper angled hemicylindrical portion 71. Seen for the firsttime in isolation are a pair of pin apertures 107 for engaging thelocking pin 87.

Referring to FIG. 9, an illustration of a side plan view and in whichthe lower tube hemicylindrical portions 65 and 69 are in matchingstraight alignment and forming a lower tube shape, while the upperangled hemicylindrical portions 67 and 71 are angled apart.

Referring to FIG. 10, a midpoint of movement is illustrates wherein thelower tube hemicylindrical portions 65 and 69 have begun to move apartwidening the lower tube shape previously formed into an angled apartopposing hemicylindrical shape, while the upper angled hemicylindricalportions 67 and 71 are brought closer together to have a closer thoughangled apart an angled apart opposing hemicylindrical shape.

Referring to FIG. 11, a completed movement, with respect to the view ofFIG. 4 illustrates a state where the lower tube hemicylindrical portions65 and 69 have moved apart to their maximum extent into a maximallyangled apart opposing hemicylindrical shape, while the upper angledhemicylindrical portions 67 and 71 are brought completely together toform an upper tube shape. It is the position of FIG. 6 which is theideal working position once the lower tube hemicylindrical portions 65and 69 are within the body, and provides an expanded working field atthe base of the working tube 35. Surgical work is ideally performedthrough the upper, abbreviated axial length tube shape formed by theupper angled hemicylindrical portions 67 and 71.

Referring to FIG. 12, a side view of the obturator 33 of FIG. 1 is seenin an assembled view and emphasizing in dashed line format a throughbore 111 which extends though the obturator 33 from the knurled knob 50through to the tip of the pair of spreading legs 39 and 41.

Referring to FIG. 13, a side view of the obturator 33 of FIG. 11 is seenin an assembled view but turned ninety degrees about its axis, and againemphasizing in dashed line format the through bore 111 which extendsthough the obturator 33 from the knurled knob 50 through to the tip ofthe pair of spreading legs 39 and 41. It is from this position thatfurther actuation will be illustrated.

Referring to FIG. 14, a side view of the obturator 33 of FIG. 13 is seenbut with the spreading legs 39 and 41 in an angled apart relationship.An optional support 112 is supported by the upper control housing 37 toenable independent support and locationing of the obturator 33 should itbe needed. Once the knurled knob 50 is turned, the wedge 51 seen in FIG.1 is driven downward causing the spreading of the spreading legs 39 and41.

Referring to FIG. 15, a sectional view taken along line 14-14 of FIG. 12gives a sectional view from the same perspective seen in FIG. 14. Pivotblocks 59 are seen as having pivot bores 113 which enable the upperportions 53 to pivot with respect to the upper control housing 37 andwhich enable the downward movement of the wedge 51 to translate into aspreading of the spreading legs 39 and 41.

As can be seen, the knob 50 and control shaft 49 and the wedge 51 havethe through bore 111. In the configuration shown, the control shaft 49includes a threaded portion 113 which engaged an internally threadedportion 115 of an internal bore 117 of the upper control housing 37. Theboss 47 is shown to be part of a larger insert fitting within a largerfitted bore 119 within the upper control housing 37. This configurationpushes the wedge 51 downwardly against an internal wedge conformingspace 123 to cause the insertion tangs 55 and upper portions 53 tospread apart. The wedge conforming space 123 need not be completelywedge shaped itself, but should ideally have a surface whichcontinuously and evenly in terms of area engages the wedge 51 to giveeven control. Further, the wedge 51 can be configured to be rotatablewith or independently rotationally stable with respect to the controlshaft 49. As can be seen, the through bore 111 continues below theinternal wedge conforming space 123 as a pair of hemicylindricalsurfaces 125 in the upper portion 53, as well as a pair ofhemicylindrical surfaces 127 in the pair of spreading legs 39 and 41.

Referring to FIG. 16 a view of obturator 33 similar to that of FIG. 15,but turned ninety degrees along its axis is seen. In this view, thewedge 51 is seen as having a narrower dimension to lend internalstability by narrowing the bearing area of the wedge 51 action inopening the pair of spreading legs 39 and 41.

Referring to FIG. 17, a closeup view of the external hinge assembly 77seen in FIG. 1 illustrates the optional use of a plug 131 to cover theexposed side of the circular protrusion 81.

Referring to FIG. 18, a view taken along line 18-18 of FIG. 11illustrates a view which facilitates the showing of an optional skirt,including a skirt section 133 welded or otherwise attached to lower tubehemicylindrical portion 65, and a skirt section 133 welded or otherwiseattached to lower tube hemicylindrical portion 69. The skirts sections133 and 135 are made of thin flexible metal and interfit within a pairof accommodation slots 137 and 139, respectively.

Referring to FIG. 19, a view of the lower tube hemicylindrical portions65 and 69 in a close relationship illustrates the manner in which theskirts sections 133 and 135 fit within the accommodation slots 137 and139 when the lower tube hemicylindrical portions 65 and 69 are broughttogether to a circular configuration.

Referring to FIG. 20, a cross sectional view of the a patient 151 spine153 is shown for illustration of the general sequence of steps taken forany procedure utilizing the minimal incision maximal access system 31.There are several procedures utilizable with the minimal incisionmaximal access system 31. Only a first procedure will be discussed usingillustrative figures. Other procedures will be discussed after minorvariations on the minimal incision maximal access system 31 are givenbelow.

Procedure I: Diskectomy and Nerve Decompression

The patient 151 is placed prone on radiolucent operating table such as aJackson Table. The patient 151 is then prepared and draped. Theoperative area is prepared and localized and an imaging device isprepared. A guide pin 155 is insert through the patient's skin 157,preferably under fluoroscopic guidance. In the alternative and or incombination, the patient 151 skin can be incised with a scalpel. Otherfeatures in FIG. 20 include the dural sac 159, and rupturedintervertebral disc 161.

Referring to FIG. 21, a fascial incisor 169 overfits the guide pin 155and is further inserted to cut through external and internal tissue. Thefascial incisor 169 is then removed while the guide pin 155 is left inplace. Next, using the obturator 33, the surgeon clears the multifidusattachment with wig-wag motion of the obturator 33 tip end. Next theobturator 33 is actuated to gently spread the multifidus muscle, andthen closed.

Referring to FIG. 22, next the assembled Working Tube 35—Obturator 33 isinserted into the area previously occupied by the fascial incisor 169and advanced to the operative level lamina and remove the obturator 33.As an alternative, and upon having difficulty, the obturator 33 could beinitially inserted, followed by an overfit of the working tube 35. Inanother possibility, a smaller size of obturator 33 and working tube 35or combination thereof could be initially utilized, followed by largersizes of the same obturator 33 and working tube 35. The assembledWorking Tube 35—Obturator 33 in place is shown in FIG. 22 with theworking ends very near the spine.

Referring to FIG. 23, the obturator 33 is actuated to a spreadorientation, which automatically actuates the working tube 35 to aspread orientation. Spread is had to the desired exposure size. Theobturator 33 is thin actuated to a closed or non-spreading position. Theobturator and working tube is then again advanced to dock on the spine.The working tube 35 is then fixed to assume an open position either byutilization of the locking pin 87 or other fixation device to cause theworking tube 35 to remain open. Then, once the working tube 35 is lockedinto an open position, the obturator 33 is actuated to a closed ornon-spread position and gently removed from the working tube 35.

Referring to FIG. 24, the working tube 35 is in place. The working tube35 may be secured by structure ultimately attached to an operatingtable. The working tube 35 may be held or stabilized in the field ofview by a support 181 which may have an engagement sleeve 183 which fitsonto the working tube. As can be seen, the operative field adjacent thespine area is expended even though the incision area is limited. Thedeeper a given size of working tube 35 is inserted, the smaller itsentrance area. After the working tube 35 is stabilized, the surgeon willtypically clear the remaining multifidus remnant at the working leveland then set up and insert an endoscope or use operating microscope orloupes. The surgeon is now ready to proceed with laminotomy.

Referring to FIG. 25, further detail on the support 181 and engagementsleeve 183 is shown. A base support 185 may support a ball joint 187,which may in turn support the support 181. The support 181 is shown assupporting a variation on the engagement sleeve 183 as a pivot pointsupport engagement end 188 having arm supports 189 and 191. The armsupports 189 and 191 engage the external pivot structure on the workingtube 35 which was shown, for example, in FIG. 1 to be the external hingeassembly 77.

As a further possibility, the upper angled hemicylindrical portions 67and 71 are shown as being engaged about their outer periphery by anadjustable clamp 195. Adjustable clamp 195 includes a band 197encircling the upper angled hemicylindrical portions 67 and 71. The endsof band 197 form a pair of opposing plates 199 and are engaged by a nut201 and bolt 203 assembly.

Referring to FIG. 26, a side view of the assembly seen in FIG. 25 isseen with the adjustable clamp 195 operable to hold the working tube 35open at any position. Referring to FIG. 27, a top view looking down uponthe adjustable clamp 195 seen in FIGS. 25-27 shows the orientation ofthe working tube 35 and adjustable clamp 195 in fully closed position.When used in conjunction with the adjustable clamp 195, the Reinforcedwear plates 73 and 93 are eliminated so as to provide a smooth interfaceagainst the exterior of the upper angled hemicylindrical portions 67 and71.

Referring to FIG. 28, a variation on the obturator 33 is seen. Anobturator 215 has handles 217 and 219 which operate about a pivot point221. A working tube 222 is somewhat simplified but is equivalent to theworking tube 35 and is shown as including upper angled hemicylindricalportions 67 and 71. Handle 219 has a ratchet member 223 extending fromit and a latch 227 pivotally connected about pivot point 229 to handle217.

Referring to FIG. 29, a variation on obturator 33 is seen as anobturator 241 having an upper housing 243, control shaft 245 having athreaded section 247 and operating through a ball nut 249. A wedge 251is extendable down through an operation space made up of a half space253 in a leg 255 and a half space 257 in a leg 259. Hinge structures 261are shown attaching the legs 255 and 259 to the upper housing 243. Athrough bore 111 is also seen as extending from the knob 261 through tothe bottom of the wedge 251. An access groove 263 is carried by the leg259 while An access groove 263 is carried by the leg 259 while an accessgroove 265 is carried by the leg 255.

Referring to FIG. 30, a sectional view taken along line 30-30 of FIG. 29illustrates the use of a central support block 271 to support the acentral threaded surface 273 and the legs 255 and 259.

Referring to FIG. 31, a view of a thin, inset hinge 281 utilizable withany of the obturators, but particularly obturators 33 and 241, is shown.In the case of obturator 33, by way of example, upper portions 53accommodate control shaft 49 with its through bore 111. Inset hinge 281may be implaced with an inset 283 and secured with machine screws 285.Inset hinge 281 may be made of a “living hinge” material such as a hardplastic, or it can have its operations base upon control bending of apre-specified length of steel, since the angle of bend is slight. Theconnection between the upper portions 53 and the upper control housing37 may be by any sort of interlocking mechanism, the aforementionedpivot blocks 59 or other mechanism.

Referring to FIG. 32, a sectional view of the obturator 33 within theworking tube 35 is seen. The wedge 51 is seen at the bottom of theinternal wedge conforming space 123. Once the spreading of the workingtube 35 is accomplished the working tube 35 is kept open by any of themethods disclosed herein. Also seen is a pivot ball 116 to allow thecontrol shaft 49 to turn with respect to the wedge. The pivot ball willcontinue to support a central aperture bore 111. Once the working tube35 is stabilized in its open position, the obturator 33 is returned toits collapsed state as is shown in FIG. 33.

Provision of electro-mechanical power to the operation of the workingtube 35 can provide a surgeon an additional degree of instant control.Referring to FIG. 34, a top and schematic view of the use of a remotepower control to provide instant control of the working tube 25, similarto the view seen in FIG. 25 illustrates the use of a remote annularcontrol cable 301 using an internal cable 303 which is closely attachedusing a guide 305 and which circles the upper angled hemicylindricalportion 67 and 71, terminating at an end fitting 307.

The annular cable 301 is controlled by a BATTERY MOTOR BOX 311 having aforward and reverse switch 313 (with off or non actuation being themiddle position). This enables the surgeon to expand the surgical fieldas needed and to collapse the surgical field to focus on certain workingareas. BATTERY MOTOR BOX 311 is configured with gears to cause the cable303 to forcibly move axially within the annular cable 301 to transmitmechanical power to the working tube 35.

Referring to FIG. 35, a view taken along line 35-35 of FIG. 34illustrates how the cable 303 is held in place and a closeup of the endtermination 307.

Referring to FIG. 36, a mechanically operated version of the nut 201 andbolt 203 constriction band seen in FIG. 25. The mechanical power linkagecan be provided remotely as by a rotating annular cable, but the basicmechanical setup shown illustrates the mechanical principles. On thebolt 203, a gear head 325 is implaced, either by attachment or by theprovision of a threaded member and gear head made together. A secondgear head 327 is utilized to show the possibility of providing a rightangle power take-off in the event that the power connection interfereswith the area around the surgical field. A shaft 329 extends from aBATTERY MOTOR BOX 331. The BATTERY MOTOR BOX 331 has a forward andreverse switch 333, (with off or non actuation being the middleposition). Shaft 329 could be flexible and connected directly into axialalignment with the threaded member of bolt 201 or an integrally formedthreaded member.

Advantages Over Existing Surgical Techniques

In terms of general advantages, there are differences between theminimal incision maximal access system 31, and its components asdescribed in all of the drawings herein (but which will be referredthroughout herein simply as the minimal incision maximal access system31, or simply system 31) and other devices and procedures.

1. With regard to the Traditional microdiskectomy technique, the minimalincision maximal access system 31 allows for at least the same, if notbetter visualization access of the operative field. System 31 offers thesame 3-Dimensional work ability or, if preferred, an endoscope can beutilized. System 31 minimizes muscle injury with spread versus extensivecautery dissection. System 31 has clear advantage on the challengingobese and very large patient where the traditional microdiskectomytechnique is almost impossible to be applied.2. With regard to open pedicle screw insertion procedures, system 31offers muscle approach minimizing muscle devascularization anddenervation. The traditional approach had required at least one levelproximal and one level distal additional exposure causing extensivemuscle injury often leading to “fibrotic” muscle changes resulting inchronic painful and stiff lower back syndrome. System 31 offers the mostdirect approach to the pedicle entry point selecting the avascular planebetween the longissimus and multifidus muscles.3. With regard to the Sextant Procedure, system 31 offers clearadvantage over the Sextant procedure. First, the system 31 offers aprocedure which is not a blind pedicle screw technique. System 31 can beapplied to larger and more obese patients in which the Sextant procedurecannot be utilized. In this procedure using system 31 oosterolateralfusion can be performed along with insertion of the pedicle screws. Thesextant procedure is strictly a tension band stabilization.

In general, the components of the minimal incision maximal access system31 are very simple the hemispherical shapes used for the working tubecan be round or oval. A keying system can be had to align the obturator33 to the working tube 35. In the case of an oval system, the alignmentwould be automatic.

The minimal incision maximal access system 31 is a modular system withinterchangeable parts for both the working tube 35 and the obturator 33.The guide Pin 155 is of simple construction, as is the fascial incisor169. The working tube 35 has a limited number of basic parts, and can bemade in the simple, two main piece version of FIG. 28, or themulti-piece version of FIG. 1, which enables retractor-sleevesubstitution. A hinge and stabilization mechanism completes thesimplified construction.

The obturator 33 is also of simple construction, with upper controlhousing 37, pair of spreading legs 39 and 41, and an internal hinge,whether the pivot blocks 59 or hinge 281 and its ability to support acontrol shaft 49 having a bore 111 for a guide pin 155. Guide pin 155may preferably have a size of from about 0.3 mm to 0.40 mm diameter and30 cm to 40 cm in length. The fascial incisor may preferably becannulated for usage with the guide pin 155 and have a width of about 2mm more than the associated retractor. The overall cutting head lengthof about 1.2 cm has a shape as indicated in the Figures and has athickness slightly larger than that of the guide pin 155.

The working tube 35 can have several variations and added detailsincluding the simplest shapes as dictated by intended usage. Workingtube 35 can have a simple fluted hemitube shape or a Slanted box shape.Further, the possibility of a fluted oval shape is dictated when theapproach is more angular. The working tube 35 can have an attachment foran endoscope. Working tube 35 can also have a non-symmetric appearanceas by having longitudinal cross sectional shape with half of its shapebeing rounded and one half of its shape being rectangular or box shaped.This could also give rise to a similarly shaped obturator 33. Theworking tube 35 should have an anti-reflective inner coating and may beof modular construction.

The preferred lower dimensions for the lower tube hemicylindricalportions 65 and 69 include an overall shape which is semi tubular roundor oval and having a width of from about 1.6-3.0 cm and a length of fromabout 4.0-18 cm. Hemicylindrical portions 65 and 69 may have custom cutouts depending upon planned application.

The hinge assembly 77 may have male-female post or male-female dial lockdesign, as well as a hinge housing and a bias (by spring or othermechanism) to keep angular displaceable portions of the working tube 35closed. A “universal” port provides a point of attachment of anendoscopic or stabilizer bar.

The obturator 33 may be any controlled opening device including acircular band or cable, force Plates, or a device attached to hingeassembly 77 or other hinge assembly.

All sleeve attachments including the attachable legs 39 and 41, as wellas the lower tube hemicylindrical portions 65 and 69 should be of thefriction grip type or snap and lock type or other suitable connectionmethod or structure.

Obturator 215 may have squeeze grip scissor style handles 219 and 217and a controlled dilator. It may utilize an enclosed design with ahandle cover having a no-slip surface. It may be attached to the hingehousing of the working tube or separate hinge housing. In fact, it maybe of a design to be held in place solely by the working tube 35.Ideally a cavity will be provided through the center axis to contain theshaft for the dilator mechanism if applicable.

The central bore 111 of the obturator 33 may have a diameter of fromabout 5-10 mm, depending upon the size of the obturator 33 utilized.Obturator 33 should be provided in various widths and length to matchworking tube. The working tips of the spreading legs 39 and 41 may bechangeable according to surgical procedures as described in theoperative procedures herein. It may have an inner chamber, or internalwedge conforming space 123 slanted in shape wider proximal and morenarrow distal to accommodate the wedge 51. The internal wedge conformingspace 123 can be enclosed with expanding, contracting sleeve.

Other Procedures

Many other procedures can be facilitated with the use of the inventiveminimal incision maximal access system 31 and methods practicedtherewith. Procedure I, a diskectomy and nerve decompression procedurewas described above with reference to the Figures. Other procedures areas follows:

Procedure II: Facet Fusion

1. Patient prone on Jackson Table with normal lordosis preserved. Thiscan be increased by placing additional thigh and chest support toincrease lumbar lordosis.

2. Insert percutaneous special guide pin perpendicular to the floor at apoint 1 cm caudal to the Alar-Superior facet notch.

3. Apply a flag guide to a first guide pin 155 #1.

4. Measure skin to bone depth from the scale on guide pin 155 #1.

5. Slide drill guide mechanism on the flag guide to match the skin bonedistance.

6. Insert guide pin 155 #2 through the drill guide to dock on thesuperior facet.

7. Make a small skin incision for the obturator 33.

8. Working tube 35 should be small oval or round with medial cutout tomaximally medialize the working tube 35.

9. Advance the working tube 35 to the L5-S1 joint and dock.

10. Drill the guide pin across the joint medial to lateral, rostral tocaudal. If in proper position, advance across the joint to engage theala.

11. Drill across the joint with a cannulated drill.

12. Check depth flouroscopically and measure.

13. Pick appropriate screw length.

14. Insert specially designed facet screw and protective bracket, securetightly.

Procedure III: Posterior Lumbar Interbody Fusion (PLIF)

1. First half of the procedure similar to microdiskectomy (Procedure I)except for the use of a larger diameter sized working tube 35. Use a20-25 mm round or elliptical diameter working tube 35 with a medialcutout to allow docking as close to midline as possible.

2. Following diskectomy enlarge the laminotomy to accommodate the toolsuse for the specific PLIF such as Brantigan cage or Tangent.

Procedure IV: Transfacet Interbody Fusion (TFIF)

1. Follow the same procedure as the PLIF in terms of selecting andinserting the Working Tube 35.

2. Following the diskectomy, resect the facet joint.

3. Approach the posterolateral disc space through the medial ⅔ of thefacet joint. Take care not to injure the exiting root above.

4. Proceed with Brantigan cage instruments and interbody cages.

Procedure V: Pedicle Screw Instrumentation Technique

1. Place the patient 151 Prone position on a Jackson Table.

2. Guide pin 155 is docked on facet joint angled 30 degree lateral tomedial in the plane between the longissimus muscle longitudinally andmultifidus muscle medially.

3. Make skin incision.

4. Fascial incisor introduction.

5. Introduce the obturator 33 working tube 35 assembly between thelongissimus and multifidus and progressively open the obturator 33 tipends of the legs 39 and 41 p, gradually reaching from the joint aboveand the joint below.

6. Advance the working tube 35 and retract the obturator 33.

7. Use the elliptical Working Tube size 2.5 cm wide and open up to 5 cm.

Procedure IV: Anterior Lateral Lumbar Diskectomy Fusion

1. Mid lateral decubitus position left side up. Place a “waist roll” toprevent sag of the mid lumbar spine.

2. Identify proper level of surgery fluoroscopically.

3. Insert a guide pin 155 #1 percutaneously into the superior facetperpendicular to the spine.

4. Measure depth skin to joint on the scaled guide pin 155 #1.

5. Insert cannulated flag guide over guide pin 155 #1.

6. Slide the drill guide to match the depth.

7. Insert a guide pin 155 #2 down to the disc space.

8. Make skin incision and insert fascial cover.

9. Insert the working tube 35 and Obturator 33 combination.

10. Progressively dilate the obturator 33.

11. Advance the working tube 35.

12. Perform anterolateral diskectomy and interbody fusion as taughtabove.

13. Use a round or oval shaped retractor or lower tube hemicylindricalportion 65 and 69 as inserts preferably with distal end cutouts in each.

Procedure VII: Posterior Cervical Foramenotomy and Lateral Mass Plating

1. The patient is placed in a prone position on a Jackson table.

2. Fluoroscopic identification of the level of surgery is had.

3. Percutaneously insert guide pin 155 with AP and lateral fluoroscopicviews.

4. Make the initial skin incision.

5. Apply the working tube 35 with obturator 33 into the incision.

6. Perform slow dilation of the muscle.

7. Advance the working tube 35 and collapse and remove the obturator 33.

8. Proceed with surgery. Type of sleeve or lower tube hemicylindricalportion 65 should be round or oval with slanted and to match the slantedlamina.

9. For application for Lateral mass plating use an oval working tube 35for a greater exposure.

Procedure VIII: Anterior Cervical Diskectomy Fusion

1. Begin with standard anterior cervical diskectomy fusion approach witha incision on the left or right side of the neck.

2. Blunt finger dissection is performed between the lateral vascularstructures and the medial strap muscle and visceral structures down tothe prevertebral fascia.

3. Establish the correct level to be operated on fluoroscopically andthe guide pin 155 inserted into the disc.

4. Apply the working tube 35 and obturator 33 combination and dock atthe proper level of the anterior spring.

5. Open the working tube 35 and obturator 33.

6. Mobilize longus colli muscle.

7. Use special Bent Homen Retractor specifically design to retract thelongus colli.

8. Proceed with surgery.

Procedure IX: Anterior Lumbar Interbody Fusion

1. Begin with the standard approach whether it is retroperitoneal,transperitoneal or laparoscopic.

2. Apply the special anterior lumbar interbody fusion working tube 35and obturator 33. This is a design with a medial lateral opening. It isoval shape and preferably with skirts 133 and 135. The distal end of theretractor sleeve is slightly flared outward to retract the vesselssafely. There is a skirt 133 or 135 applied to the cephalad side andpossibly to the caudal side.

3. With the vessels and the abdominal contents safely retracted out ofharms way, proceed with diskectomy and fusion.

While the present system 31 has been described in terms of a system ofinstruments and procedures for facilitating the performance of amicroscopic lumbar diskectomy procedure, one skilled in the art willrealize that the structure and techniques of the present system 31 canbe applied to many appliances including any appliance which utilizes theembodiments of the instrumentation of the system 31 or any process whichutilizes the steps of the system 31.

Although the system 31 has been derived with reference to particularillustrative embodiments thereof, many changes and modifications of thesystem 31 may become apparent to those skilled in the art withoutdeparting from the spirit and scope of the system 31. Therefore,included within the patent warranted hereon are all such changes andmodifications as may reasonably and properly be included within thescope of this contribution to the art.

1-2. (canceled)
 3. An obturator comprising: a first pivoting memberhaving a first end, a second end, and a first pivot surface between saidfirst and second ends, said first pivoting member between said firstpivot surface and said first end forming a first exteriorhemicylindrical surface; a second pivoting member having a first end, asecond end, and a second pivot surface between said first and secondends and in pivoting contact with said first pivot surface, said secondpivoting member between said first pivot surface and said first endforming a second exterior hemicylindrical surface, said first and secondexterior hemicylindrical surfaces forming a cylindrical section whenbrought into close relation with each other; and a ratchet mechanismconnected between said first and said second pivoting members toselectably hold said first and said second exterior hemicylindricalsurfaces apart from each other.
 4. The obturator of claim 3, whereinsaid ratchet mechanism further comprises a curved ratchet member havinga first end attached to said first pivoting member, said ratchet memberhaving a series of teeth along said curved ratchet member, and a latchsupported from and movable with respect to said second pivoting memberand a selectably engaging the teeth of said curved ratchet member. 5.The obturator of claim 3, wherein a length between said second ends ofsaid first and said second pivoting members and a pivot point form amanual handle portion and wherein said ratchet mechanism is farther fromsaid pivot point than said manual handle portion.
 6. The obturator ofclaim 3, wherein said first and second pivoting member second ends arehingeably attached to each other.
 7. The obturator of claim 3, whereinsaid first and second pivoting members each form a part of a controlshaft for accommodating a guide pin.
 8. The obturator of claim 3 furtherincluding at least one spreading leg, the at least one spreading leghaving: an upper portion having an insertion tang; and a lower spreadingleg portion having an insertion slot for interfitting with saidinsertion tang.
 9. An obturator and working tube kit for performing asurgical procedure at a location in a patient's body comprising theobturator of claim 3 and a working tube.